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([43.135.149.86]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22ac7c95cdcsm53279515ad.118.2025.04.11.11.31.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Apr 2025 11:31:23 -0700 (PDT) From: alexjlzheng@gmail.com X-Google-Original-From: alexjlzheng@tencent.com To: gregkh@linuxfoundation.org, tj@kernel.org Cc: alexjlzheng@tencent.com, linux-kernel@vger.kernel.org Subject: [PATCH kernfs 1/3] kernfs: switch global kernfs_idr_lock to per-fs lock Date: Sat, 12 Apr 2025 02:31:07 +0800 Message-ID: <20250411183109.6334-2-alexjlzheng@tencent.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250411183109.6334-1-alexjlzheng@tencent.com> References: <20250411183109.6334-1-alexjlzheng@tencent.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jinliang Zheng The kernfs implementation has big lock granularity(kernfs_idr_lock) so every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the lock. This patch switches the global kernfs_idr_lock to per-fs lock, which put the spinlock into kernfs_root. Signed-off-by: Jinliang Zheng Acked-by: Tejun Heo --- fs/kernfs/dir.c | 14 +++++++------- fs/kernfs/kernfs-internal.h | 1 + 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index fc70d72c3fe8..355d943ffe27 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -27,7 +27,6 @@ DEFINE_RWLOCK(kernfs_rename_lock); /* kn->parent and ->na= me */ */ static DEFINE_SPINLOCK(kernfs_pr_cont_lock); static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by pr_cont_lock */ -static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ =20 #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) =20 @@ -584,9 +583,9 @@ void kernfs_put(struct kernfs_node *kn) if (kernfs_type(kn) =3D=3D KERNFS_LINK) kernfs_put(kn->symlink.target_kn); =20 - spin_lock(&kernfs_idr_lock); + spin_lock(&root->kernfs_idr_lock); idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); - spin_unlock(&kernfs_idr_lock); + spin_unlock(&root->kernfs_idr_lock); =20 call_rcu(&kn->rcu, kernfs_free_rcu); =20 @@ -639,13 +638,13 @@ static struct kernfs_node *__kernfs_new_node(struct k= ernfs_root *root, goto err_out1; =20 idr_preload(GFP_KERNEL); - spin_lock(&kernfs_idr_lock); + spin_lock(&root->kernfs_idr_lock); ret =3D idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); if (ret >=3D 0 && ret < root->last_id_lowbits) root->id_highbits++; id_highbits =3D root->id_highbits; root->last_id_lowbits =3D ret; - spin_unlock(&kernfs_idr_lock); + spin_unlock(&root->kernfs_idr_lock); idr_preload_end(); if (ret < 0) goto err_out2; @@ -681,9 +680,9 @@ static struct kernfs_node *__kernfs_new_node(struct ker= nfs_root *root, return kn; =20 err_out3: - spin_lock(&kernfs_idr_lock); + spin_lock(&root->kernfs_idr_lock); idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); - spin_unlock(&kernfs_idr_lock); + spin_unlock(&root->kernfs_idr_lock); err_out2: kmem_cache_free(kernfs_node_cache, kn); err_out1: @@ -989,6 +988,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_sy= scall_ops *scops, return ERR_PTR(-ENOMEM); =20 idr_init(&root->ino_idr); + spin_lock_init(&root->kernfs_idr_lock); init_rwsem(&root->kernfs_rwsem); init_rwsem(&root->kernfs_iattr_rwsem); init_rwsem(&root->kernfs_supers_rwsem); diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 40a2a9cd819d..24e9514565ac 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -40,6 +40,7 @@ struct kernfs_root { =20 /* private fields, do not use outside kernfs proper */ struct idr ino_idr; + spinlock_t kernfs_idr_lock; /* root->ino_idr */ u32 last_id_lowbits; u32 id_highbits; struct kernfs_syscall_ops *syscall_ops; --=20 2.48.1